After much thought, I went to MT to have my W204 tuned by Alvin.
I opted for custom ECU tune. Performance of the car improved and was pleased.
However, i feel the gear change was sluggish and soon after, contacted Alvin again for transmission tune and installation of throttle controller.
Installing transmission map was a breeze and gear shift was much more repsonsive. Didn't get to install throttle controller at the same time due to stock availability but it was a blessing as I can know the improvement of each maps or hardware after installation.
Finally got throttle controller installed yesterday. I'm really happy with the results! Compliment with tunings and throttle controller, I'm driving a new experience in my 5 years owned car. Enjoying every moment of it now.
Great job and thanks to Alvin and team.

That's great to come with your ride.
I measured the dimension of the bolt and bought this. Mcgard, OEM for Merc wheel lock.
https://www.amazon.com/gp/product/B00498OUQ4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I presume you are using BMC. I've no experience since I have been using either OEM or K&N filter in all my previous ride.
Can you give me some feedback on BMC?
BMC cost is definitely more compared to K&N.